
import javax.servlet.*;
import javax.servlet.http.*;
import java.io.IOException;

public class sy1 extends HttpServlet {

    protected void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {

        String username = request.getParameter("username");
        String password = request.getParameter("password");
        String captchaInput = request.getParameter("captcha");

        // 假设已经实现了验证码验证函数
        boolean isValidCaptcha = verifyCaptcha(captchaInput); // 在实际项目中实现此函数

        if (isValidCaptcha) {
            // 验证用户名和密码（此处仅作演示，实际要连接数据库）
            if (username.equals("admin") && password.equals("password")) {
                // 登录成功，转发至主页
                RequestDispatcher dispatcher = request.getRequestDispatcher("/success.html");
                dispatcher.forward(request, response);
            } else {
                // 登录失败
                response.getWriter().println("Invalid username or password.");
            }
        } else {
            // 验证码错误
            response.sendRedirect("/login.html?error=captcha");
        }
    }
    
    // 在实际项目中实现验证码验证逻辑
    private boolean verifyCaptcha(String captchaInput) {
        // 获取真实的验证码并进行比较
        // 示例中直接返回false，代表验证失败
        return false; 
    }
}